Abnormality detection apparatus for resolver

ABSTRACT

To provide an abnormality detection apparatus for resolver which can determine the abnormality of at least the first system, even if the period of the excitation AC voltage of the first system and the period of the excitation AC voltage of the second system are different periods, and the magnetic interference between systems occurs. An abnormality detection apparatus for resolver applies an AC voltage of a first period to a first system excitation winding; applies an AC voltage of a second period different from the first period to a second system excitation winding; calculates DC values of first system two output signals by performing a DC extraction processing; and determines abnormality of first system based on whether or not the DC values of first system two output signals are within a normal range.

TECHNICAL FIELD

The present disclosure is related with an abnormality detection apparatus for resolver.

BACKGROUND ART

As the angle detection device which detects the rotational angle of the motor, the resolver is used well. Although the resolver is known as the robust angle detection device, the resolver is also required for redundancy from the request of the fault tolerance of the motor drive system.

Then, the patent document 1 discloses the dual system resolver which is provided with the first system excitation winding and output winding, and the second system excitation winding and output winding.

The patent document 2 discloses the technology that the first and the second resolver sensors are provided, and it is determined that signal wires of both resolvers short-circuited, when the amplitude sin ωt of the output signal of sine phase and the amplitude cos ωt of the output signal of cosine phase do not satisfy the relation of (sin ωt)²+(cos Ωt)²=1 about each resolver sensor.

Although it does not have redundancy, the patent document 3 discloses the technology that, in the angle detection device which outputs the sine wave signal and the cosine wave signal according to the rotor position of the brushless DC motor, failure of the angle detection device is detected based on whether or not the sum of a square value of the sine wave signal and a square value of the cosine wave signal becomes within the predetermined range.

CITATION LIST Patent Literature

-   Patent document 1: JP 2000-18968 A -   Patent document 2: JP 2005-147791 A -   Patent document 3: JP 2006-335252 A

SUMMARY OF INVENTION Technical Problem

However, in the redundant system resolver like the patent document 1 and 2, even if electrically insulated between the first system and the second system which configure the redundant system, a magnetic interference occurs. Accordingly, in the output signal of the output winding in one of the first system and the second system, a component resulting from the excitation AC voltage in the other of the first system and the second system is included. For example, in the output signal of the output winding in the first system, in addition to the component resulting from the excitation AC voltage applied to the first system excitation winding, the component resulting from the excitation AC voltage applied to the second system excitation winding is included. Similarly, also in the output signal of the output winding in the second system, in addition to the component resulting from the excitation AC voltage applied to the second system excitation winding, the component resulting from the excitation AC voltage applied to the first system excitation winding is included.

The patent document 1 does not disclose the technology of determining the abnormality of each system, in this kind resolver which has the first system and the second system. The patent document 3 does not disclose the technology of determining the abnormality of each system, in the redundant system resolver.

In the technology of patent document 2, the phases of the output signals of the sine phase and the cosine phase of the first resolver, and the phases of the output signals of the sine phase and the cosine phase of the second resolver are different 180 degrees. The period of the AC voltage applied to the excitation winding of the first resolver, and the period of the AC voltage applied to the excitation winding of the second resolver are made the same periods. Accordingly, in the patent document 2, although the influence of the magnetic interference between the first system and the second system is not indicated, even if the magnetic interference occurs, the component resulting from the excitation winding of the first resolver and the component resulting from the excitation winding of the second resolver, which are included in the output signals of the sine phase and the cosine phase of the first resolver, become inverse phases. Accordingly, the amplitude gains of the output signals of the sine phase and the cosine phase only decrease, but the relation of (sin ωt)²+(cos Ωt)²=1 is maintained.

Therefore, like the technology of the patent document 2, if the period of the AC voltage applied to the first system excitation winding and the period of the AC voltage applied to the second system excitation winding are the same periods, and the phases of the first system two output signals and the phases of the second system two output signals become the same phases or inverse phases, even if the magnetic interference between systems occurs, it is thought that abnormality can be determined based on the square sum of two output signals, about each system.

However, if the period of the AC voltage applied to the first system excitation winding and the period of the AC voltage applied to the second system excitation winding are different periods, as mentioned above, due to the component resulting from the excitation AC voltage of the second system included in the first system two output signals, and the vibration component of the period of the excitation AC voltage of the second system is superimposed on the square sum of the first system two output signals. Accordingly, based on the square sum, abnormality of first system cannot be determined with good accuracy. Similarly, based on the square sum of the second system two output signals, abnormality of second system cannot be determined with good accuracy.

In order to improve redundancy, it is required to provide a resolver in which the first system and the second system can be operated independently with each other, the synchronization between the excitation AC voltage of the first system and the excitation AC voltage of the second system is not required, and the period of the excitation AC voltage of the first system and the period of the excitation AC voltage of the second system are different periods.

Then, the purpose of the present disclosure is to provide an abnormality detection apparatus for resolver which can determine the abnormality of at least the first system, even if the period of the excitation AC voltage of the first system and the period of the excitation AC voltage of the second system are different periods, and the magnetic interference between systems occurs.

Solution to Problem

An abnormality detection apparatus for resolver according to the present disclosure including:

a resolver that is provided with a first system excitation winding, first system two output windings, a second system excitation winding, and second system two output windings, in which magnetic interference occurs between a first system and a second system;

a first system excitation unit that applies AC voltage of a first period to the first system excitation winding;

a second system excitation unit that applies AC voltage of a second period different from the first period, to the second system excitation winding;

a first system output signal detection unit that detects output signals of the first system two output windings at a period less than or equal to half of the first period;

a first system reduction processing unit that performs a second period component reduction processing which reduces component of the second period, to detection values of the output signals of the first system two output windings;

a first system DC extraction processing unit that calculates DC values of the first system two output signals, by performing a DC extraction processing which reduces component of the first period, to the detection values of output signals of first system two output windings after the second period component reduction processing; and

a first system abnormality detection unit that determines abnormality of first system, based on whether or not the DC values of first system two output signals are within a preliminarily set normal range of first system.

Advantage of Invention

When there is abnormality in the first system, vibration center values of the components of the first period included in the detection values of output signals of first system two output windings deviate from the normal range. According to the abnormality detection apparatus for resolver of the present disclosure, in the case where the first period and the second period are different, and the components of the second period resulting from the excitation AC voltage of the second period of the second system are included in the detection values of output signals of first system two output windings due to the magnetic interference between systems, the components of the second period can be reduced from the detection values of output signals of first system two output windings, by the second period component reduction processing. Then, by performing the DC extraction processing which reduces the components of the first period, to the detection values of output signals of first system two output windings after the second period component reduction processing, the vibration center values (DC components) of the components of the first period included in the detection values of output signals of first system two output windings can be calculated. Accordingly, the abnormality of first system can be determined with good accuracy, based on whether or not the DC values of first system two output signals are within the normal range of first system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of the abnormality detection apparatus for resolver according to Embodiment 1;

FIG. 2 is a side view of the resolver viewed in the axial direction according to Embodiment 1;

FIG. 3 is a time chart for explaining the first system detection timing when supposing that there is no magnetic interference between systems according to Embodiment 1;

FIG. 4 is a hardware configuration diagram of the controller according to Embodiment 1.

FIG. 5 is a time chart for explaining the second period component reduction processing and the DC extraction processing of the first system according to Embodiment 1;

FIG. 6 is a block diagram of the first system reduction processing unit according to Embodiment 1;

FIG. 7 is a flowchart explaining the abnormality detection processing of the first system according to Embodiment 1;

FIG. 8 is a flowchart explaining another example of the abnormality detection processing of the first system according to Embodiment 1;

FIG. 9 is a time chart for explaining the first period component reduction processing and the DC extraction processing of the second system according to Embodiment 1;

FIG. 10 is a block diagram of the second system reduction processing unit according to Embodiment 1;

FIG. 11 is a flowchart explaining the abnormality detection processing of the second system according to Embodiment 1;

FIG. 12 is a flowchart explaining another example of the abnormality detection processing of the second system according to Embodiment 1;

FIG. 13 is a time chart for explaining the first period component reduction processing and the DC extraction processing of the second system according to Embodiment 2;

FIG. 14 is a block diagram of the second system reduction processing unit according to Embodiment 2;

FIG. 15 is a schematic configuration diagram of the abnormality detection apparatus for resolver according to Embodiment 3; and

FIG. 16 is a schematic perspective view of the resolver according to Embodiment 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS 1. Embodiment 1

An abnormality detection apparatus for resolver according to Embodiment 1 is explained with reference to drawings. FIG. 1 is a schematic configuration diagram of the abnormality detection apparatus for resolver according to the present embodiment. The abnormality detection apparatus for resolver is also an angle detection apparatus.

1-1. Resolver 1

The resolver 1 is provided with a first system excitation winding 10A, first system two output windings 111A, 112A (referred to also as a first system first output winding 111A and a first system second output winding 112A), a second system excitation winding 10B, and second system two output windings 111B, 112B (referred to also as a second system first output winding 111B and a second system second output winding 112B). A magnetic interference occurs between the first system windings and the second system windings. That is to say, by electromagnetic induction due to the magnetic flux generated by the first system excitation winding 10A, an induced voltage is generated not only in the first system two output windings 111A, 112A, but also in the second system two output windings 111B, 112B; and by electromagnetic induction due to the magnetic flux generated by the second system excitation winding 10B, an induced voltage is generated not only in the second system two output windings 111B, 112B, but also in the first system two output windings 111A, 112A.

As shown in FIG. 2 , the first system excitation winding 10A, the first system two output windings 111A, 112A, the second system excitation winding 10B, and second system two output windings 111B, 112B are wound around the same one stator 13. The rotor 14 is arranged in the radial-direction inner side of the stator 13. The rotor 14 is provided with a plurality of projection parts which are arranged equally in the circumferential direction on the peripheral part of the rotor. The projection height to the radial-direction outside of the projection parts is formed so that the gap permeance between the stator 13 and the rotor 14 changes in sine wave shape according to rotation. That is to say, the resolver 1 is a variable reluctance (VR) type resolver. In the present embodiment, the five projection parts are provided, and the shaft angle multiplier is 5. Therefore, whenever the rotor rotates once in the mechanical angle, rotates 5 times in the electrical angle.

As showing an example supposed that there is no magnetic interference between two systems in FIG. 3 , when the rotor rotates in the state where the AC voltage VRA is applied to the first system excitation winding 10A, the amplitude of AC voltage V1A induced by the first system first output winding 111A and the amplitude of AC voltage V2A induced by the first system second output winding 112A change in a sine wave shape (or in a cosine wave shape), according to the rotational angle (the gap permeance) in the electrical angle of the rotor. The first system first output winding 111A and the first system second output winding 112A are wound around the positions of the circumferential direction of the stator 13 so that the amplitudes of those AC voltages are mutually different 90 degrees in the electrical angle. Similarly, the second system first output winding 111B and the second system second output winding 112B are wound around the positions of the circumferential direction of the stator 13 so that the amplitudes of those induced AC voltages are mutually different 90 degrees in the electrical angle.

In the present embodiment, as shown in FIG. 2 , the stator 13 is provided with 12 teeth arranged equally in the circumferential direction; the first system windings are wound around the first teeth TEl to the sixth teeth TE6; and the second system windings are wound around the seventh teeth TE7 to the twelfth teeth TE12. The first system excitation winding 10A is distributed and wound around the first teeth TEl to the sixth teeth TE6. The first system first output winding 111A and the first system second output winding 112A are distributed and wound around the first teeth TEl to the sixth teeth TE6 so that the amplitudes of those induced AC voltages are mutually different 90 degrees in the electrical angle. Similarly, the second system excitation winding 10B is distributed and wound around the seventh teeth TE7 to the twelfth teeth TE12. The second system first output winding 111B and the second system second output winding 112B are distributed and wound around the seventh teeth TE7 to the twelfth teeth TE12 so that the amplitudes of those induced AC voltages are mutually different 90 degrees in the electrical angle.

The first system excitation winding 10A wound around the plurality of teeth is connected in series between teeth; and the two terminals of the first system excitation winding 10A connected in series are connected to the controller 50 (the first system excitation unit 51A) described below. Similarly, the two terminals of the first system first output winding 111A connected in series between teeth are connected to the controller 50 (the first system output signal detection unit 52A) described below. The two terminals of the first system second output winding 112A connected in series between teeth are connected to the controller 50 (the first system output signal detection unit 52A) described below. The two terminals of the second system excitation winding 10B wound around the plurality of teeth are connected to the controller 50 (the second system excitation unit 51B) described below. Similarly, the two terminals of the second system first output winding 111B connected in series between teeth are connected to the controller 50 (the second system output signal detection unit 52B) described below. The two terminals of the second system second output winding 112B connected in series between teeth are connected to the controller 50 (the second system output signal detection unit 52B) described below.

The number of projection parts (shaft angle multiplier) and the number of teeth may be set to any numbers. The first system windings and the second system windings may not be arranged being divided into two in the circumferential direction, but may be arranged being distributed in the circumferential direction.

1-2. Controller 50

The abnormality detection apparatus for resolver is provided with a controller 50. As shown in FIG. 1 , the controller 50 is provided with a first system excitation unit S1A, a first system output signal detection unit 52A, a first system reduction processing unit 53A, a first system angle calculation unit 54A, a first system DC extraction processing unit 55A, a first system abnormality detection unit 56A, a second system excitation unit 51B, a second system output signal detection unit 52B, a second system reduction processing unit 53B, a second system angle calculation unit 54B, a second system DC extraction processing unit 55B, and a second system abnormality detection unit 56B. Each function of the controller 50 is realized by processing circuits provided in the controller 50.

Specifically, as shown in FIG. 4 , the controller 50 includes, as a processing circuit, a arithmetic processor (computer) 90 such as a CPU (Central Processing Unit), storage apparatuses 91 which exchange data with the arithmetic processor 90, an input circuit 92 which inputs external signals to the arithmetic processor 90, an output circuit 93 which outputs signals from the arithmetic processor 90 to the outside, and the like.

As the arithmetic processor 90, ASIC (Application Specific Integrated Circuit), IC (Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), various kinds of logical circuits, various kinds of signal processing circuits, and the like may be provided. As the arithmetic processor 90, a plurality of the same type ones or the different type ones may be provided, and each processing may be shared and executed. As the storage apparatuses 91, there are provided a RAM (Random Access Memory) which can read data and write data from the arithmetic processor 90, a ROM (Read Only Memory) which can read data from the arithmetic processor 90, and the like. The first system first output winding 111A, the first system second output winding 112A, the second system first output winding 111B, and the second system second output winding 112B are connected to the input circuit 92. The input circuit 92 is provided with an A/D converter and the like for inputting the output voltages of these windings into the arithmetic processor 90. The output circuit 93 is connected with the first system excitation winding 10A and the second system excitation winding 10B, and is provided with driving circuits, such as switching devices for applying the AC voltage VRA to these windings. A lowpass filter circuit may be provided in the output side of the switching device. The output circuit 93 is provided with signal output circuits, such as a communication circuit which transmits the first angle θ1, the second angle θ2, the first system abnormality signal ERR1, and the second system abnormality signal ERR2 which were calculated to the external controller 94.

Then, the arithmetic processor 90 runs software items (programs) stored in the storage apparatus 91 such as a ROM and collaborates with other hardware devices in the controller 50, such as the storage apparatus 91, the input circuit 92, and the output circuit 93, so that the respective functions of the control units 51A to 56B included in the controller 50 are realized. Setting data utilized in the control units 51A to 56B are stored, as part of software items (programs), in the storage apparatus 91 such as a ROM. Each function of the controller 50 will be described in detail below.

1-2-1. Excitation Unit

The first system excitation unit S1A applies AC voltage VRA (in this example, AC voltage VRA of a sine wave) of first period TA to the first system excitation winding 10A. The first system excitation unit 51A calculates an AC voltage command of the first period TA, and generates the PWM signal (Pulse Width Modulation) which turns on and off the switching device for the first system excitation winding provided in the output circuit 93, based on the comparison result between the AC voltage command and the triangular wave. When the switching device is turned on, the power source voltage is applied to the first system excitation winding 10A side, and when the switching device is turned off, the application of the power source voltage stops.

The second system excitation unit 51B applies AC voltage VRB (in this example, AC voltage VRB of a sine wave) of second period TB to the second system excitation winding 10B. The second period TB is set to a period different from the first period TA. In the present embodiment, as described later, the second period TB is set to two times of the first period TA (TB=2×TA). For example, in the case of TA-50 microseconds, it is set as TB-100 microseconds.

The second system excitation unit 51B calculates an AC voltage command of the second period TB, and generates the PWM signal (Pulse Width Modulation) which turns on and off the switching device for the second system excitation winding provided in the output circuit 93, based on the comparison result between the AC voltage command and the triangular wave.

1-2-2. First System Output Signal Detection Unit

The first system output signal detection unit 52A detects periodically the output signals V1A, V2A of the first system two output windings 111A, 112A at preliminarily set detection timing. In the present embodiment, as described later, the detection timing is set considering first system abnormality determination and angle calculation.

1-2-3. First System Reduction Processing Unit <Problem Due to Magnetic Interference Between Systems>

As showing an example of the output signal V1A of the first system first output winding in FIG. 5 , the components of the second period V1A_TB, V2A_TB induced by electromagnetic induction due to the magnetic flux of the second period TB excited in the second system excitation winding 10B are superimposed on each of the output signals V1A, V2A of the first system two output windings 111A, 112A, due to the magnetic interference between systems. The output signal V1A of the first system first output winding is shown in the upper row graph of FIG. 5 ; the component of the first period V1A_TA induced by electromagnetic induction due to the magnetic flux of the first system excitation winding 10A included in the output signal V1A of the first system first output winding is shown in the middle graph; and the component of the second period V1A_TB induced by electromagnetic induction due to the magnetic flux of the second system excitation winding 10B included in the output signal V1A of the first system first output winding is shown in the lower row graph. The output signal V1A of the first system first output winding becomes a signal obtained by totaling the component of the first period V1A_TA and the component of the second period V1A_TB.

<Second Period Component Reduction Processing>

Then, the first system reduction processing unit 53A performs a second period component reduction processing which reduces component of the second period, to the detection values of output signals of first system two output windings V1A_S, V2A_S.

In the present embodiment, the second period component reduction processing is performed based on a principle explained in the following. As shown in the lower row graph of FIG. 5 , in the component of the second period V1A_TB of the output signal of the first system first output winding, the phase is reversed and the sign of plus or minus is reversed at a period (for example, half period TB/2 of the second period) obtained by adding an integral multiple of the second period TB to a half period TB/2 of the second period.

Then, as the second period component reduction processing, the first system reduction processing unit 53A adds the detection values of output signals of first system two output windings V1A_S, V2A_S detected at this time detection timing, and the detection values of output signals of first system two output windings V1A_Sold, V2A_Sold detected at a detection timing earlier by the first system reduction processing interval ΔT1 than this time detection timing. The first system reduction processing interval ΔT1 is set as shown in the next equation. Herein, M is an integer greater than or equal to 0. In the present embodiment, M is set to 0, and the first system reduction processing interval ΔT1 is set to the half period TB/2 of the second period.

ΔT1=TB/2+TB×M  (1)

The first system reduction processing unit 53A is constituted, for example, as shown in FIG. 6 . The first system reduction processing unit 53A is provided with a first delay device 53A1 which delays the detection value V1A_S of the output signal of the first system first output winding by the first system reduction processing interval ΔT1, and outputs; adds the detection value V1A_S of the output signal of the first system first output winding, and the output V1A_Sold of the first delay device 53A1; and calculates the detection value V1A_F of the output signal of the first system first output winding after the second period component reduction processing. Similarly, the first system reduction processing unit 53A is provided with a second delay device 53A2 which delays the detection value V2A_S of the output signal of the first system second output winding by the first system reduction processing interval ΔT1, and outputs; adds the detection value V2A_S of the output signal of the first system second output winding, and the output V2A_Sold of the second delay device 53A2; and calculates the detection value V2A_F of the output signal of the first system second output winding after the second period component reduction processing.

According to this configuration, the two components of the second period whose signs of plus or minus are reversed with each other are added, and the two components of the second period are canceled with each other. Accordingly, in the detection values of output signals of first system two output windings V1A_F, V2A_F after addition, the component of the second period is reduced. Then, using the components of the first period of the first system in which the component of the second period of the second system was reduced, the first system abnormality determination described below can be performed with good accuracy.

In the present embodiment, the second period TB is set to an even multiple of the first period TA, as shown in the next equation. Herein, N is an integer greater than or equal to 1. In the present embodiment, N is set to 1, and the second period TB is set to a twice of the first period TA. For example, if the first period TA is set to 50 microseconds, the second period TB is set to 100 microseconds.

TB=TA×2×N  (2)

According to this configuration, as shown in the next equation in which the equation (2) is substituted in the equation (1), the first system reduction processing interval ΔT1 becomes an integral multiple of the first period TA.

ΔT1=TA×(N+2×N×M)  (3)

Therefore, among the detection values of output signals of first system two output windings V1A_S, V2A_S, values before and after the integral multiple of the first period TA are added. Then, as shown in FIG. 5 , since the added two components of the first period have the same phase, and become the equivalent values with the same sign of plus or minus, the detection values of output signals of first system two output windings V1A_F, V2A_F after addition correspond to the double values of the components of the first period V1A_TA, V2A_TA included in the detection values, respectively.

V1A_F≈2×V1A_TA

V2A_F≈2×V2A_TA  (4)

In the present embodiment, M is set to 0, and N is set to 1. Therefore, the first system reduction processing unit 53A adds the detection values of output signals of first system two output windings V1A_S, V2A_S detected at this time detection timing, and the detection values of output signals of first system two output windings V1A_Sold, V2A_Sold detected before the first period TA (the half period TB/2 of the second period).

1-2-4. First System Abnormality Determination <Principle of Abnormality Determination>

The detection values of output signals of first system two output windings V1A_F, V2A_F after the second period component reduction processing (hereinafter, referred to also as the first system two output signals V1A_F, V2A_F after the second period component reduction processing) become behavior similar to the detection values of output signals of first system two output windings V1A_S, V2A_S if there is no magnetic interference between the systems shown in FIG. 3 . Therefore, when there is no abnormality in the first system, the first system two output signals V1A_F, V2A_F after the second period component reduction processing vibrate at the first period TA centering on a fixed voltage, and amplitudes vibrate at the rotation period. Even using instantaneous values of the first system two output signals V1A_F, V2A_F after the second period component reduction processing which are vibrating in this way, it is hard to determine the presence or absence of abnormality. On the other hand, when there is no abnormality, since the vibration center value becomes a fixed normal value. Accordingly, when the vibration center value is varied from the normal value, it can be detected that abnormality occurred.

In order to calculate the vibration center values of the first system two output signals V1A_F, V2A_F after the second period component reduction processing which are vibrating at the first period TA, it is necessary to sample the output signals at a period less than or equal to half of the first period TA according to the sampling theorem.

<Detection Period for Abnormality Determination>

Then, the first system output signal detection unit 52A detects periodically the output signals V1A, V2A of the first system two output windings 111A, 112A at a detection period for first system abnormality determination which is set to a period less than or equal to half of the first period TA. In the present embodiment, as shown in FIG. 5 , the first system output signal detection unit 52A detects the output signal of the first system two output windings V1A_S, V2A_S at a detection timing of every half period TA/2 of the first period when the AC voltage VRA of the first period TA applied to the first system excitation winding 10A becomes the maximum value or the minimum value.

<Second Period Component Reduction Processing for Abnormality Determination>

Then, the first system reduction processing unit 53A calculates the first system two output signals V1A_F, V2A_F after the second period component reduction processing, by performing the second period component reduction processing to the detection values of the first system two output signals V1A_S, V2A_S at every half period TA/2 of the first period when the first system two output signals V1A_S, V2A_S are detected. In the present embodiment, the first system reduction processing unit 53A calculates the first system two output signals V1A_F, V2A_F after the second period component reduction processing, by adding the detection values of the first system two output signals V1A_S, V2A_S detected at this time, and the detection values of the first system two output signals V1A_Sold, V2A_Sold detected before the first system reduction processing interval ΔT1 (in this example, before the first period TA (it may be before an integral multiple of the first period TA)), at every detection period for abnormality determination (in this example, every half period TA/2 of the first period).

<First System DC Extraction Processing Unit>

The first system DC extraction processing unit 55A calculates DC values of first system two output signals V1A_DC, V2A_DC, by performing a DC extraction processing which reduces component of the first period TA, to the first system two output signals V1A_F, V2A_F after the second period component reduction processing, respectively.

In the present embodiment, the first system DC extraction processing unit 55A calculates the DC values of first system two output signals V1A_DC, V2A_DC, by performing a moving average processing during the first period TA, to the first system two output signals V1A_F, V2A_F after the second period component reduction processing, respectively. In this example, the detection timing for abnormality determination and the timing of the second period component reduction processing are set to the timing of every half period TA/2 of the first period. Accordingly, as shown in the next equation, the first system DC extraction processing unit 55A calculates, as the DC values of first system two output signals V1A_DC, V2A_DC, average values of the first system two output signals V1A_F, V2A_F after the second period component reduction processing calculated at this time detection timing, and the first system two output signals V1A_F_old, V2A_F_old after the second period component reduction processing calculated at the last time detection timing which is before the half period TA/2 of the first period.

V1A_DC={V1A_F+V1A_F_old}/2

V2A_DC={V2A_F+V2A_F_old}/2  (5)

As explained using the equation (4), the first system two output signals V1A_F, V2A_F after the second period component reduction processing correspond to the double values of the components of the first period V1A_TA, V2A_TA. Accordingly, as seen from the behavior of component of the first period V1A_TA shown in FIG. 9 , phases of the first system two output signals V1A_F, V2A_F after the second period component reduction processing calculated at this time, and phases of the first system two output signals V1A_F_old, V2A_F_old after the second period component reduction processing calculated at last time of before the half period TA/2 of the first period are reversed. Accordingly, by calculating average values of both, the vibration center values of the components of the first period V1A_TA, V2A_TA can be calculated.

Alternatively, the first system DC extraction processing unit 55A may calculate the DC values of first system two output signals V1A_DC, V2A_DC, by performing a moving average processing during a period of a natural number (2 or more) times of the first period TA, to the first system two output signals V1A_F, V2A_F after the second period component reduction processing.

Alternatively, the first system DC extraction processing unit 55A may calculate the DC values of first system two output signals V1A_DC, V2A_DC, by performing a band stop filter processing which reduces component of band including frequency of the first period TA, to the first system two output signals V1A_F, V2A_F after the second period component reduction processing. Alternatively, the first system DC extraction processing unit 55A may calculate the DC values of first system two output signals V1A_DC, V2A_DC, by performing a low pass filter processing with a cutoff frequency smaller than frequency of the first period TA, to the first system two output signals V1A_F, V2A_F after the second period component reduction processing.

On the other hand, in the case where the second period component reduction processing is not performed unlike the present embodiment, and components of the second period are superimposed on the first system two output signals, as shown in FIG. 5 , since phase of the component of the second period T1A_TB varies by 90 degrees at every half period TA/2 of the first period, the vibration components of the second period TB are superimposed on the DC values of first system two output signals, and the vibration center values of the components of the first period V1A_TA, V2A_TA cannot be calculated with good accuracy.

<First System Abnormality Detection Unit>

The first system abnormality detection unit 56A determines abnormality of first system, based on whether or not the DC values of first system two output signals V1A_DC, V2A_DC are within a preliminarily set normal range of first system, respectively.

As mentioned above, the DC values of first system two output signals V1A_DC, V2A_DC correspond to the vibration center values of the components of the first period V1A_TA, V2A_TA included in the detection values of the first system two output signals V1A_S, V2A_S.

The normal range of first system is set to a range between a lower limit value of first system MIN1 and an upper limit value of first system MAX1, in which normal values of the vibration center values of the components of the first period V1A_TA, V2A_TA are included. For example, the lower limit value of first system MIN1 is preliminarily set to a value smaller than the normal values (in this example, 0) of the vibration center values of the components of the first period V1A_TA, V2A_TA by a predetermined value; and the upper limit value of first system MAX1 is preliminarily set to a value larger than the normal values of the vibration center values by a predetermined value. The normal range of first system is adjusted in accordance with the degree of abnormality to be determined as abnormal.

In the case where the voltage ranges of the first system two output signals are 0 to 5V unlike the present embodiment and the normal values of the vibration center values are 2.5V, the normal range of first system is set to a range in which 2.5V is included.

The abnormality of first system includes abnormality of disconnection of each winding 10A, 111A, 112A of the first system, abnormality of the input and output circuit of each winding of the first system in the controller 50, abnormality of processing related to the first system of the controller 50, and the like.

Processing of the abnormality determination is explained using the flowchart of FIG. 7 . Processing of the flowchart of FIG. 7 is executed after calculating the DC values of first system two output signals V1A_DC, V2A_DC at every detection period for abnormality determination. Although FIG. 7 explains the abnormality determination which uses the DC value V1A_DC of the output signal of first system first output winding, it is similarly performed about the DC value V2A_DC of the output signal of first system second output winding.

In the step S01, the first system abnormality detection unit 56A acquires the DC value V1A_DC of the output signal of the first system first output winding calculated by the first system DC extraction processing unit 55A. Then, in the step S02, the first system abnormality detection unit 56A determines whether or not the DC value V1A_DC of the output signal of first system first output winding is greater than or equal to the lower limit value of first system MIN1, and is less than or equal to the upper limit value of first system MAX1. That is to say, the first system abnormality detection unit 56A determines whether or not the DC value V1A_DC of the output signal of first system first output winding is within the normal range of first system.

When the first system abnormality detection unit 56A determines that the DC value V1A_DC of the output signal of first system first output winding is not within the normal range of first system in the step S02, it advances to the step S03 and determines that the abnormality of first system occurred. In the present embodiment, the first system abnormality detection unit 56A outputs a first system abnormality signal ERR1, when determining that the abnormality of first system occurred. For example, the first system abnormality signal ERR1 is transmitted to the external controller 94 to which the first angle 81 is transmitted. If the controller 50 and the external controller 94 are integrated, the first system abnormality signal ERR1 is transmitted in the same controller.

On the other hand, when the first system abnormality detection unit 56A determines that the DC value V1A_DC of the output signal of first system first output winding is within the normal range of first system in the step S02, it determines that the abnormality of first system does not occur, and ends processing.

<Another Example of Abnormality Determination Processing>

Another example of processing of abnormality determination is explained using the flowchart of FIG. 8 . Processing of the flowchart of FIG. 8 is executed after calculating the DC values of first system two output signals V1A_DC, V2A_DC at every detection period for abnormality determination. Although FIG. 8 explains the abnormality determination which uses the DC value V1A_DC of the output signal of first system first output winding, it is similarly performed about the DC value V2A_DC of the output signal of first system second output winding.

In the step S11, the first system abnormality detection unit 56A acquires the DC value V1A_DC of the output signal of the first system first output winding calculated by the first system DC extraction processing unit 55A. Then, in the step S12, the first system abnormality detection unit 56A determines whether or not the DC value V1A_DC of the output signal of first system first output winding is greater than or equal to the lower limit value of first system MIN1, and is less than or equal to the upper limit value of first system MAX1. That is to say, the first system abnormality detection unit 56A determines whether or not the DC value V1A_DC of the output signal of first system first output winding is within the normal range of first system.

When the first system abnormality detection unit 56A determines that the DC value V1A_DC of the output signal of first system first output winding is not within the normal range of first system in the step S12, it advances to the step S13 and increases the abnormality determination counter T1 by one. After that, it advances to the step S14, and the first system abnormality detection unit 56A determines whether or not the abnormality determination counter T1 is greater than or equal to a preliminarily set abnormality determination frequency T1 ab.

When the first system abnormality detection unit 56A determines that the abnormality determination counter T1 is greater than or equal to the abnormality determination frequency T1 ab in the step S14, it advances to the step S15 and determines that the abnormality of first system occurred. Then, the first system abnormality detection unit 56A outputs the first system abnormality signal ERR1, when determining that the abnormality of first system occurred. When the first system abnormality detection unit 56A determines that the abnormality determination counter T1 is not greater than or equal to the abnormality determination frequency T1 ab in the step S14, it determines that the abnormality of first system does not occur, and ends processing.

On the other hand, when the first system abnormality detection unit 56A determines that the DC value V1A_DC of the output signal of first system first output winding is within the normal range of first system in the step S12, it advances to the step S16, after resetting the abnormality determination counter T1 to 0, ends processing.

In the example of the flowchart of FIG. 8 , when a case where the DC value V1A_DC of the output signal of first system first output winding is not within the normal range of first system occurs continuously the preliminarily set abnormality determination frequency T1 ab or more, the first system abnormality detection unit 56A determines that abnormality occurred in the first system.

In this way, by performing determination by the abnormality determination frequency T1 ab, erroneous determination can be prevented from occurring due to noise component generated in the DC value V1A_DC of the output signal of first system first output winding. By determining that abnormality occurred when it is not within the normal range continuously, accuracy of abnormality determination can be improved.

In the step S16, the first system abnormality detection unit 56A may not reset the abnormality determination counter T1 to 0, but may hold the abnormality determination counter T1 to the previous value, or may decrease the abnormality determination counter T1.

1-2-5. First System Angle Calculation Unit

As shown in the next equation, the first system angle calculation unit 54A calculates the first angle θ1 by calculating an arc tangent (an arc tangent function) of a ratio between the output signal V1A_F of the first system first output winding and the output signal V2A_F of the first system second output winding after the second period component reduction processing.

θ1=tan⁻¹(V1A_F/V2A_F)  (6)

As shown in the equation (4), the output signals of first system two output windings V1A_F, V2A_F after the second period component reduction processing correspond to the double values of the components of the first period V1A_TA, V2A_TA included in the detection values, respectively. Therefore, as shown in the next equation in which the equation (4) is substituted in the equation (6), the first angle θ1 is calculated with good accuracy by the ratio of the components of the first period V1A_TA, V2A_TA included in the detection values.

$\begin{matrix} {{{\theta 1} \approx {\tan^{- 1}\left\{ {\left( {2 \times {V1A\_ TA}} \right)/\left( {2 \times {V2A\_ TA}} \right)} \right\}}} = {\tan^{- 1}\left( {{V1A\_ TA}/{V2A\_ TA}} \right)}} & (7) \end{matrix}$

Although the first angle θ1 may be calculated at every calculation of the first system two output signals V1A_F, V2A_F after the second period component reduction processing (in this example, every half period TA/2 of the first period), as shown in FIG. 3 , the first angle θ1 is calculated at the calculation timing when the AC voltage VRA of the first period TA applied to the first system excitation winding 10A becomes the maximum value or the minimum value (in the example of FIG. 3 , the maximum value).

1-2-6. Second System Output Signal Detection Unit

The second system output signal detection unit 52B detects periodically the output signals V1B, V2B of the second system two output windings 111B, 112B at a preliminarily set detection timing. In the present embodiment, as described later, the detection timing is set considering second system abnormality determination and angle calculation.

1-2-7. Second System Reduction Processing Unit <Problem Due to Magnetic Interference Between Systems>

As showing an example of the output signal V1B of the second system first output winding in FIG. 9 , the components of the first period induced by the magnetic flux of the first period TA excited in the first system excitation winding 10A are superimposed on each of the output signals V1B, V2B of the second system two output windings 111B, 112B, due to the magnetic interference between systems. The output signal V1B of the second system first output winding is shown in the upper row graph of FIG. 9 ; the component of the second period V1B_TB induced by electromagnetic induction of the magnetic flux of the second system excitation winding 10B included in the output signal V1B of the second system first output winding is shown in the middle graph; and the component of the first period V1B_TA induced by electromagnetic induction of the magnetic flux of the first system excitation winding 10A included in the output signal V1B of the second system first output winding is shown in the lower row graph. The output signal V1B of second system first output winding becomes a signal obtained by totaling the component of the second period V1B_TB and the component of the first period V1B_TA.

<First Period Component Reduction Processing>

Then, the second system reduction processing unit 53B performs a first period component reduction processing which reduces component of the first period, to the detection values of output signals of second system two output windings V1B_S, V2B_S.

In the present embodiment, the first period component reduction processing is performed based on a principle explained in the following. As shown in the lower row graph of FIG. 9 , the component of the first period V1B_TA of the output signal of second system first output winding becomes the same value at every first period TA, since its period is the first period TA.

Then, as the first period component reduction processing, the second system reduction processing unit 53B performs a subtraction processing that calculates differences between the detection values of output signals of second system two output windings V1B_S, V2B_S detected at this time detection timing, and the detection values of output signals of second system two output windings V1B_Sold, V2B_Sold detected at the detection timing earlier by the second system reduction processing interval ΔT2 than this time detection timing. The second system reduction processing interval ΔT2 is set to an integral multiple of the first period TA, as shown in the next equation. Herein, P is an integer greater than or equal to 1. In the present embodiment, P is set to 1, and the second system reduction processing interval ΔT2 is set to the first period TA.

ΔT2=TA×P  (8)

The second system reduction processing unit 53B is constituted, for example, as shown in FIG. 10 . The second system reduction processing unit 53B is provided with a first delay device 53B1 which delays the detection value V1B_S of the output signal of the second system first output winding by the second system reduction processing interval ΔT2, and outputs; subtracts the output V1B_Sold of the first delay device 53B1 from the detection value V1B_S of the output signal of the second system first output winding; and calculates the detection value V1B_F of the output signal of the second system first output winding after the first period component reduction processing. Similarly, the second system reduction processing unit 53B is provided with a second delay device 53B2 which delays the detection value V2B_S of the output signal of the second system second output winding by the second system reduction processing ΔT2, and outputs; subtracts the output V2B_Sold of the second delay device 53B2 from the detection value V2B_S of the output signal of the second system second output winding; and calculates the detection value V2B_F of the output signal of the second output winding after the first period component reduction processing.

According to this configuration, the two components of the first period which become the equivalent values with the same sign of plus or minus with each other are subtracted, and the two components of the first period are canceled with each other. Accordingly, in the detection values of output signals of second system two output windings V1B_F, V2B_F after the subtraction processing, the component of the first period is reduced. Then, using the components of the second period of the second system in which the component of the first period of the first system was reduced, the second system abnormality determination described below can be performed with good accuracy.

As mentioned above, in the present embodiment, the second period TB is set to an even multiple of the first period TA, as shown in the next equation. Herein, N is an integer greater than or equal to 1. In the present embodiment, N is set to 1, and the second period TB is set to a twice of the first period TA.

TB=TA×2×N  (9)

The second reduction processing ΔT2 is set as shown in the next equation. Herein, L is an integer greater than or equal to 0. In the present embodiment, L is set to 0, and the second system reduction processing interval ΔT2 is set to the half period TB/2 of the second period.

ΔT2=TB/2+TB×L  (10)

Even in this case, if the equation (9) is substituted in the equation (10), the second system reduction processing interval ΔT2 becomes an integral multiple of the first period TA similarly to the equation (8), as shown in the next equation. Therefore, as mentioned above, by the first period component reduction processing (the subtraction processing), the components of the first period can be reduced.

ΔT2=TA×N×(1+2×L)  (11)

By setting the second system reduction processing interval ΔT2 like the equation (10), in the two components of the second period subtracted by the subtraction processing, the phases are reversed and the signs of plus or minus are reversed, as shown in FIG. 9 . Therefore, the detection values of output signals of second system two output windings V1B_F, V2B_F after the subtraction processing correspond to the double values of the components of the second period V1B_TB, V2B_TB included in the detection values, respectively.

V1B_F≈2×V1B_TB

V2B_F≈2×V2B_TB  (12)

In the present embodiment, L is set to 0, N is set to 1, and P is set to 1. Therefore, the second system reduction processing unit 53B subtracts the detection values of output signals of second system two output windings V1B_Sold, V2B_Sold detected before the half period TB/2 of the second period (the first period TA), from the detection values of output signals of second system two output windings V1B_S, V2B_S detected at this time detection timing.

1-2-8. Second System Abnormality Determination <Principle of Abnormality Determination>

The detection values of output signals of second system two output windings V1B_F, V2B_F after the first period component reduction processing (hereinafter, referred to also as the second system two output signals V1B_F, V2B_F after the first period component reduction processing) become behavior similar to the detection values of output signals of second system two output windings V1B_S, V2B_S if there is no magnetic interference between the systems shown in FIG. 3 . Therefore, when there is no abnormality in the second system, the second system two output signals V1B_F, V2B_F after the first period component reduction processing vibrate at the second period TB centering on a fixed voltage, and amplitudes vibrate at the rotation period. Even using instantaneous values of the second system two output signals V1B_F, V2B_F after the first period component reduction processing which are vibrating in this way, it is hard to determine the presence or absence of abnormality. On the other hand, when there is no abnormality, since the vibration center value becomes a fixed normal value. Accordingly, when the vibration center value is varied from the normal value, it can be detected that abnormality occurred.

In order to calculate the vibration center values of the second system two output signals V1B_F, V2B_F after the first period component reduction processing which are vibrating at the second period TB, it is necessary to sample the output signals at a period less than or equal to half of the second period TB according to the sampling theorem.

<Detection Period for Abnormality Determination>

Then, the second system output signal detection unit 52B detects periodically the output signals V1B, V2B of the second system two output windings 111B, 112B at a detection period for second system abnormality determination which is set to a period less than or equal to half of the second period TB. In the present embodiment, as shown in FIG. 9 , the second system output signal detection unit 52B detects the output signals of the second system two output windings V1B_S, V2B_S at a detection timing of every half period TB/2 of the second period when the AC voltage VRB of the second period TB applied to the second system excitation winding 10B becomes the maximum value or the minimum value.

<First Period Component Reduction Processing for Abnormality Determination>

Then, the second system reduction processing unit 53B calculates the second system two output signals V1B_F, V2B_F after the first period component reduction processing, by performing the first period component reduction processing to the detection values of the second system two output signals V1B_S, V2B_S at every half period TB/2 of the second period when the second system two output signals V1B_S, V2B_S are detected. The second system reduction processing unit 53B calculates the second system two output signals V1B_F, V2B_F after the first period component reduction processing, by subtracting, from the detection values of the second system two output signals V1B_S, V2B_S detected at this time, the detection values of the second system two output signals V1B_Sold, V2B_Sold detected before the second system reduction processing interval ΔT2 (in this example, before the second period TB (it may be before an integral multiple of the second period TB)), at every detection period for abnormality determination (in this example, every half period TB/2 of the second period).

<Second System DC Extraction Processing Unit>

The second system DC extraction processing unit 55B calculates DC values of second system two output signals V1B_DC, V2B_DC, by performing a DC extraction processing which reduces component of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing, respectively.

In the present embodiment, the second system DC extraction processing unit 55B calculates the DC values of second system two output signals V1B_DC, V2B_DC, by performing a moving average processing during the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing, respectively. In this example, the detection timing for abnormality determination and the timing of the first period component reduction processing are set to the timing of every half period TB/2 of the second period. Accordingly, as shown in the next equation, the second system DC extraction processing unit 55B calculates, as the DC values of second system two output signals V1B_DC, V2B_DC, average values of the second system two output signals V1B_F, V2B_F after the first period component reduction processing calculated at this time detection timing, and the second system two output signals V1B_F_old, V2B_F_old after the first period component reduction processing calculated at the last time detection timing which is before the half period TB/2 of the second period.

V1B_DC={V1B_F+V1B_F_old}/2

V2B_DC={V2B_F+V2B_F_old}/2  (13)

As explained using the equation (12), the second system two output signals V1B_F, V2B_F after the first period component reduction processing correspond to the double values of the components of the second period V1B_TB, V2B_TB. Accordingly, as seen from the behavior of component of the second period V1B_TB shown in FIG. 9 , phases of the second system two output signals V1B_F, V2B_F after the first period component reduction processing calculated at this time, and phases of the second system two output signals V1B_F_old, V2B_F_old after the first period component reduction processing calculated at last time of before the half period TB/2 of the second period are reversed. Accordingly, by calculating average values of both, the vibration center values of the components of the second period V1B_TB, V2B_TB can be calculated.

Alternatively, the second system DC extraction processing unit 55B may calculate the DC values of second system two output signals V1B_DC, V2B_DC, by performing a moving average processing during a period of a natural number (2 or more) times of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing.

Alternatively, the second system DC extraction processing unit 55B may calculate the DC values of second system two output signals V1B_DC, V2B_DC, by performing a band stop filter processing which reduces component of band including frequency of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing. Alternatively, the second system DC extraction processing unit 55B may calculate the DC values of second system two output signals V1B_DC, V2B_DC, by performing a low pass filter processing with a cutoff frequency smaller than frequency of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing.

On the other hand, in the case where the first period component reduction processing is not performed unlike the present embodiment, and components of the first period are superimposed on the second system two output signals, as shown in FIG. 9 , since the component of the first period T1B_TA becomes the same value at every half period TB/2 of the second period, the components of the first period TA are superimposed on the DC values of second system two output signals in an offset manner. Since the offset values are varied according to a phase difference between the second period TB and the first period TA, the vibration center values of the components V1B_TB, V2B_TB of the second period cannot be calculated with good accuracy.

<Second System Abnormality Detection Unit>

The second system abnormality detection unit 56B determines abnormality of second system, based on whether or not the DC values of second system two output signals V1B_DC, V2B_DC are within a preliminarily set normal range of second system, respectively.

As mentioned above, the DC values of second system two output signals V1B_DC, V2B_DC correspond to the vibration center values of the components of the second period V1B_TB, V2B_TB included in the detection values of the second system two output signals V1B_S, V2B_S.

The normal range of second system is set to a range between a lower limit value of second system MIN2 and an upper limit value of second system MAX2, in which normal values of the vibration center values of the components of the second period V1B_TB, V2B_TB are included. For example, the lower limit value of second system MIN2 is preliminarily set to a value smaller than the normal values (in this example, 0) of the vibration center values of the components of the second period V1B_TB, V2B_TB by a predetermined value; and the upper limit value of second system MAX2 is preliminarily set to a value larger than the normal values of the vibration center values by a predetermined value. The normal range of second system is adjusted in accordance with the degree of abnormality to be determined as abnormal.

In the case where the voltage ranges of the second system two output signals are 0 to 5V unlike the present embodiment and the normal values of the vibration center values are 2.5V, the normal range of second system is set to a range in which 2.5V is included.

The abnormality of second system includes abnormality of disconnection of each winding 10B, 111B, 112B of the second system, abnormality of the input and output circuit of each winding of the second system in the controller 50, abnormality of processing related to the second system of the controller 50, and the like.

Processing of the abnormality determination is explained using the flowchart of FIG. 11 . Processing of the flowchart of FIG. 11 is executed after calculating the DC values of second system two output signals V1B_DC, V2B_DC at every detection period for abnormality determination. Although FIG. 11 explains the abnormality determination which uses the DC value V1B_DC of the output signal of second system first output winding, it is similarly performed about the DC value V2B_DC of the output signal of second system second output winding.

In the step S31, the second system abnormality detection unit 56B acquires the DC value V1B_DC of the output signal of the second system first output winding calculated by the second system DC extraction processing unit 55B. Then, in the step S32, the second system abnormality detection unit 56B determines whether or not the DC value V1B_DC of the output signal of second system first output winding is greater than or equal to the lower limit value of second system MIN2, and is less than or equal to the upper limit value of second system MAX2. That is to say, the second system abnormality detection unit 56B determines whether or not the DC value V1B_DC of the output signal of second system first output winding is within the normal range of second system.

When the second system abnormality detection unit 56B determines that the DC value V1B_DC of the output signal of second system first output winding is not within the normal range of second system in the step S32, it advances to the step S33 and determines that the abnormality of second system occurred. In the present embodiment, the second system abnormality detection unit 56B outputs a second system abnormality signal ERR2, when determining that the abnormality of second system occurred. For example, the second system abnormality signal ERR2 is transmitted to the external controller 94 to which the second angle 92 is transmitted. If the controller 50 and the external controller 94 are integrated, the second system abnormality signal ERR2 is transmitted in the same controller.

On the other hand, when the second system abnormality detection unit 56B determines that the DC value V1B_DC of the output signal of second system first output winding is within the normal range of second system in the step S32, it determines that the abnormality of second system does not occur, and ends processing.

<Another Example of Abnormality Determination Processing>

Another example of processing of abnormality determination is explained using the flowchart of FIG. 12 . Processing of the flowchart of FIG. 12 is executed after calculating the DC values of second system two output signals V1B_DC, V2B_DC at every detection period for abnormality determination. Although FIG. 12 explains the abnormality determination which uses the DC value V1B_DC of the output signal of second system first output winding, it is similarly performed about the DC value V2B_DC of the output signal of second system second output winding.

In the step S41, the second system abnormality detection unit 56B acquires the DC value V1B_DC of the output signal of the second system first output winding calculated by the second system DC extraction processing unit 55B. Then, in the step S42, the second system abnormality detection unit 56B determines whether or not the DC value V1B_DC of the output signal of second system first output winding is greater than or equal to the lower limit value of second system MIN2, and is less than or equal to the upper limit value of second system MAX2. That is to say, the second system abnormality detection unit 56B determines whether or not the DC value V1B_DC of the output signal of second system first output winding is within the normal range of second system.

When the second system abnormality detection unit 56B determines that the DC value V1B_DC of the output signal of second system first output winding is not within the normal range of second system in the step S42, it advances to the step S43 and increases the abnormality determination counter T2 by one. After that, it advances to the step S44, and the second system abnormality detection unit 56B determines whether or not the abnormality determination counter T2 is greater than or equal to a preliminarily set abnormality determination frequency T2 ab.

When the second system abnormality detection unit 56B determines that the abnormality determination counter T2 is greater than or equal to the abnormality determination frequency T2 ab in the step S44, it advances to the step S45 and determines that the abnormality of second system occurred. Then, the second system abnormality detection unit 56B outputs the second system abnormality signal ERR2, when determining that the abnormality of second system occurred. When the second system abnormality detection unit 56B determines that the abnormality determination counter T2 is not greater than or equal to the abnormality determination frequency T2 ab in the step S44, it determines that the abnormality of second system does not occur, and ends processing.

On the other hand, when the second system abnormality detection unit 56B determines that the DC value V1B_DC of the output signal of second system first output winding is within the normal range of second system in the step S42, it advances to the step S46, after resetting the abnormality determination counter T2 to 0, ends processing.

In the example of the flowchart of FIG. 12 , when a case where the DC value V1B_DC of the output signal of second system first output winding is not within the normal range of second system occurs continuously the preliminarily set abnormality determination frequency T2 ab or more, the second system abnormality detection unit 56B determines that abnormality occurred in the second system.

In this way, by performing determination by the abnormality determination frequency T2 ab, erroneous determination can be prevented from occurring due to noise component generated in the DC value V1B_DC of the output signal of second system first output winding. By determining that abnormality occurred when it is not within the normal range continuously, accuracy of abnormality determination can be improved.

In the step S46, the second system abnormality detection unit 56B may not reset the abnormality determination counter T2 to 0, but may hold the abnormality determination counter T2 to the previous value, or may decrease the abnormality determination counter T2.

1-2-9. Second System Angle Calculation Unit

As shown in the next equation, the second system angle calculation unit 54B calculates the second angle θ2 by calculating an arc tangent (an arc tangent function) of a ratio between the output signal V1B_F of the second system first output winding and the output signal V2B_F of the second system second output winding after the first period component reduction processing.

θ2=tan⁻¹(V1B_F/V2B_F)  (14)

As shown in the equation (12), the output signals of the second system two output windings V1B_F, V2B_F after the first period component reduction processing correspond to the double values of the components of the second period V1B_TB, V2B_TB included in the detection values, respectively. Therefore, as shown in the next equation in which the equation (12) is substituted in the equation (14), the second angle θ2 is calculated with good accuracy by the ratio of the components of the second period V1B_TB, V2B_TB included in the detection values.

$\begin{matrix} {{{\theta 2} \approx {\tan^{- 1}\left\{ {\left( {2 \times {V1B\_ TB}} \right)/\left( {2 \times {V2B\_ TB}} \right)} \right\}}} = {\tan^{- 1}\left( {{V1B\_ TB}/{V2B\_ TB}} \right)}} & (15) \end{matrix}$

Although the second angle θ2 may be calculated at every calculation of the second system two output signals V1B_F, V2B_F after the first period component reduction processing (in this example, every half period TB/2 of the second period), the second angle θ2 is calculated at the calculation timing when the AC voltage VRB of the second period TB applied to the second system excitation winding 10B becomes the maximum value or the minimum value (for example, the maximum value).

It is only required that the setting values of the first period TA, the second period TB, the first system detection timing, the second system detection timing, the first system reduction processing interval ΔT1, and the second system reduction processing interval ΔT2 are preliminarily set to become the predetermined relation between the first system and the second system; the processing of the first system and the processing of the second system can be performed independently with each other; and it is not necessary to perform synchronous control in real time between the first system and the second system.

2. Embodiment 2

Next, the abnormality detection apparatus for resolver according to Embodiment 2 will be explained. The explanation for constituent parts the same as those in Embodiment 1 will be omitted. The basic configuration of the abnormality detection apparatus for resolver according to the present embodiment is the same as that of Embodiment 1. Embodiment 2 is different from Embodiment 1 in configuration of the second system output signal detection unit 52B, the second system reduction processing unit 53B, and the second system DC extraction processing unit 55B of the controller 50.

The second system output signal detection unit 52B detects periodically the output signals V1B, V2B of the second system two output windings 111B, 112B at a preliminarily set detection timing. Also in the present embodiment, as described later, the detection timing is set considering second system abnormality determination and angle calculation.

<Problem Due to Magnetic Interference Between Systems>

As showing an example of the output signal V1B of the second system first output winding in FIG. 13 , the components of the first period induced by electromagnetic induction of the magnetic flux of the first period TA excited in the first system excitation winding 10A are superimposed on each of the output signals V1B, V2B of the second system two output windings 111B, 112B, due to the magnetic interference between systems. The output signal V1B of the second system first output winding is shown in the upper row graph of FIG. 13 ; the component of the second period V1B_TB induced by electromagnetic induction of the magnetic flux of the second system excitation winding 10B included in the output signal V1B of the second system first output winding is shown in the middle graph; and the component of the first period V1B_TA induced by electromagnetic induction of the magnetic flux of the first system excitation winding 10A included in the output signal V1B of the second system first output winding is shown in the lower row graph. The output signal V1B of second system first output winding becomes a signal obtained by totaling the component of the second period V1B_TB and the component of the first period V1B_TA.

<First Period Component Reduction Processing>

Also in the present embodiment, the second system reduction processing unit 53B performs a first period component reduction processing which reduces component of the first period, to the detection values of output signals of second system two output windings V1B_S, V2B_S.

In the present embodiment, unlike Embodiment 1, the first period component reduction processing is performed based on a principle explained in the following. As shown in the lower row graph of FIG. 13 , in the component of the first period V1B_TA of the output signal of the second system first output winding, the phase is reversed and the sign of plus or minus is reversed in a period (for example, half period TA/2 of the second period) obtained by adding an integral multiple of the first period TA to a half period TA/2 of the first period.

Then, as the first period component reduction processing, the second system reduction processing unit 53B adds the detection values of output signals of second system two output windings V1B_S, V2B_S detected at this time detection timing, and the detection values of output signals of second system two output windings V1B_Sold, V2B_Sold detected at the detection timing earlier by the second system reduction processing interval ΔT2 than this time detection timing. The second system reduction processing interval ΔT2 is set to an interval obtained by adding an integral multiple of the first period TA to the half period TA/2 of the first period, as shown in the next equation. Herein, X is an integer greater than or equal to 0. In the present embodiment, X is set to 0, and the second system reduction processing interval ΔT2 is set to the half period TA/2 of the first period.

ΔT2=TA/2+TA×X  (16)

According to this configuration, the two components of the first period whose signs of plus or minus are reversed with each other are added, and the two components of the first period are canceled with each other. Accordingly, in the detection values of output signals of second system two output windings V1B_F, V2B_F after addition, the components of the first period are reduced. Then, using the components of the second period of the second system in which the component of the first period of the first system was reduced, the second system abnormality determination described below can be performed with good accuracy.

In the present embodiment, as shown in FIG. 13 , the second system output signal detection unit 52B detects periodically the output signals of second system two output windings V1B, V2B at two timings TM1, TM2 which become before-and-after symmetrical with respect to a reference timing TM0 when the AC voltage VRB of the second period TB applied to the second system excitation winding 10B becomes the maximum value or the minimum value.

An interval between two timings which become before-and-after symmetry is set to the second system reduction processing interval ΔT2. Therefore, as shown in the next equation, an interval ΔTM12 between each of before-and-after two timings TM1, TM2 and the reference timing TM0 is set to the half of the second system reduction processing interval ΔT2.

ΔTM12=ΔT2/2  (17)

Then, the second system reduction processing unit 53B adds the detection values of output signals of second system two output windings detected at the two timings TM1, TM2 which become before-and-after symmetry, with each other; and calculates the detection values of output signals of second system two output windings V1B_F, V2B_F after the first period component reduction processing.

According to this configuration, as shown in FIG. 13 , the components of the second period included in the detection values of output signals of second system two output windings detected at two timings have the same phase, and become the equivalent values with the same sign of plus or minus. Since the interval between two timings TM1, TM2 is set to the second system reduction processing interval ΔT2, in the components of the first period included in the detection values of output signals of second system two output windings detected at two timings TM1, TM2, the phases are reversed and the signs of plus or minus are reversed. Therefore, the detection values of output signals of second system two output windings V1B_F, V2B_F after addition correspond to the double values of the components of the second period V1B_TB, V2B_TB included in the detection values, respectively.

V1B_F≈2×V1B_TB

V2B_F=2×V2B_TB  (18)

The second system reduction processing unit 53B is constituted, for example, as shown in FIG. 14 . The second system reduction processing unit 53B is provided with a first delay device 53B1 which delays the detection value V1B_S of the output signal of the second system first output winding by the second system reduction processing interval ΔT2, and outputs; adds the detection value V1B_S of the output signal of the second system first output winding and the output V1B_Sold of the first delay device 53B1, at the timing TM2 after the reference timing TM0; and calculates the detection value V1B_F of the output signal of the second system first output winding after the first period component reduction processing. Similarly, the second system reduction processing unit 53B is provided with a second delay device 53B2 which delays the detection value V2B_S of the output signal of the second system second output winding by the second system reduction processing interval ΔT2, and outputs; adds the detection value V2B_S of the output signal of the second system second output winding and the output V2B_Sold of the second delay device 53B2, at the timing TM2 after the reference timing TM0; and calculates the detection value V2B_F of the output signal of the second system second output winding after the first period component reduction processing.

In the present embodiment, as shown in the next equation, the second period TB is set to twice of the first period TA. The second system reduction processing interval ΔT2 is set to the half period TA/2 of the first period. Therefore, the interval ΔTM12 between each of before-and-after two timings TM1, TM2 and the reference timing TM0 is set to ¼ period TA/4 of the first period.

TB=TA×2

ΔT2=TA/2

ΔTM12=TA/4  (19)

The second system output signal detection unit 52B detects the output signals of second system two output windings V1B, V2B at every ¼ period TB/4 of the second period; and each detection timing is set so as to become before-and-after symmetrical with respect to the reference timing TM0 when the AC voltage VRB of the second period TB becomes the maximum value or the minimum value.

<Abnormality of Second System Determination>

The second system output signal detection unit 52B detects periodically the output signals V1B, V2B of the second system two output windings 111B, 112B at a detection period for second system abnormality determination which is set to a period less than or equal to half of the second period TB. In the present embodiment, as shown in FIG. 13 , the second system output signal detection unit 52B detects the output signals of second system two output windings V1B_S, V2B_S at timing (TM1, TM2) of every ¼ period of the second period TB.

Then, the second system reduction processing unit 53B calculates the second system two output signals V1B_F, V2B_F after the first period component reduction processing as described above, at later timing TM2 of the two timings of every half period TB/2 of the second period.

The second system DC extraction processing unit 55B calculates DC values of second system two output signals V1B_DC, V2B_DC, by performing a DC extraction processing which reduces component of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing, respectively.

In the present embodiment, the second system DC extraction processing unit 55B calculates the DC values of second system two output signals V1B_DC, V2B_DC, by performing a moving average processing during the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing, respectively. As shown in the next equation, the second system DC extraction processing unit 55B calculates, as the DC values of second system two output signals V1B_DC, V2B_DC, average values of the second system two output signals V1B_F, V2B_F after the first period component reduction processing calculated at this time later timing TM2, and the second system two output signals V1B_F_old, V2B_F_old after the first period component reduction processing calculated at the last time later timing TM2 which is before the half period TB/2 of the second period.

V1B_DC={V1B_F+V1B_F_old}/2

V2B_DC={V2B_F+V2B_F_old}/2  (20)

As explained using the equation (18), the second system two output signals V1B_F, V2B_F after the first period component reduction processing correspond to the double values of the components of the second period V1B_TB, V2B_TB. Accordingly, as seen from the behavior of component of the second period V1B_TB shown in FIG. 13 , phases of the second system two output signals V1B_F, V2B_F after the first period component reduction processing calculated at this time later timing TM2, and phases of the second system two output signals V1B_F_old, V2B_F_old after the first period component reduction processing calculated at last time later timing TM2 which is before the half period TB/2 of the second period are reversed. Accordingly, by calculating average values of both, the vibration center values of the components of the second period V1B_TB, V2B_TB can be calculated.

Alternatively, the second system DC extraction processing unit 55B may calculate the DC values of second system two output signals V1B_DC, V2B_DC, by performing a moving average processing during a period of a natural number (2 or more) times of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing.

Alternatively, the second system DC extraction processing unit 55B may calculate the DC values of second system two output signals V1B_DC, V2B_DC, by performing a band stop filter processing which reduces component of band including frequency of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing. Alternatively, the second system DC extraction processing unit 55B may calculate the DC values of second system two output signals V1B_DC, V2B_DC, by performing a low pass filter processing with a cutoff frequency smaller than frequency of the second period TB, to the second system two output signals V1B_F, V2B_F after the first period component reduction processing.

On the other hand, in the case where the first period component reduction processing is not performed unlike the present embodiment, and components of the first period are superimposed on the second system two output signals, as shown in FIG. 13 , since the component of the first period T1B_TA becomes the same value at every half period TB/2 of the second period, the vibration components of the first period TA are superimposed on the DC values of second system two output signals in an offset manner, and the vibration center values of the components of the second period V1B_TB, V2B_TB cannot be calculated with good accuracy.

3. Embodiment 3

Next, the abnormality detection apparatus for resolver according to Embodiment 3 will be explained. The explanation for constituent parts the same as those in each of Embodiments 1 or 2 will be omitted. The basic configuration of the abnormality detection apparatus for resolver according to the present embodiment is the same as that of Embodiment 1. But, the configuration of the resolver 1 is different from Embodiment 1 or 2. FIG. 15 is a schematic configuration diagram of the angle detection apparatus according to the present embodiment.

Similarly to Embodiment 1, the resolver 1 is provided with the first system excitation winding 10A, the first system two output windings 111A, 112A, the second system excitation winding 10B, and the second system two output windings 111B, 112B. A magnetic interference occurs between the first system windings and the second system windings.

However, in the present embodiment, unlike Embodiment 1 and 2, as the schematic diagram of the resolver 1 is shown in FIG. 16 , the first system excitation winding 10A and the first system two output windings 111A, 112A are wound around the first system stator 13A; and the second system excitation winding 10B and the second system two output windings 111B, 112B are wound around the second system stator 13B. The first system stator 13A and the second system stator 13B are arranged adjacent to each other in the axial direction; and a magnetic interference occurs between the first system windings and the second system windings. In FIG. 16 , the teeth and the windings of the first system stator 13A, and the teeth and the windings of the second system stator 13B are omitted in figure.

The first system stator 13A and the second system stator 13B are coaxially arranged adjacent to each other in the axial direction; and the rotor 14 formed integrally is arranged in the radial-direction inner side of the first system stator 13A and the second system stator 13B. The rotor 14 is provided with a plurality of projection parts which are arranged equally in the circumferential direction on the peripheral part of the rotor. In the present embodiment, the rotor part located in the radial-direction inner side of the first system stator 13A and the rotor part located in the radial-direction inner side of the second system stator 13B have the same shape of the projection parts. The rotor part of the radial-direction inner side of the first system stator 13A and the rotor part of the radial-direction inner side of the second system stator 13B may have the different shapes and the different numbers of the projection parts with each other; and these may be the different bodies connected so as to rotate integrally.

The first system stator 13A is provided with a plurality of teeth arranged equally in the circumferential direction. The first system first output winding 111A and the first system second output winding 112A are distributed and wound around each teeth of the first system stator 13A so that the amplitudes of those induced AC voltages are mutually different 90 degrees in the electrical angle. The first system excitation winding 10A is distributed and wound around each teeth of the first system stator 13A. The second system stator 13B is provided with a plurality of teeth arranged equally in the circumferential direction. The second system first output winding 111B and the second system second output winding 112B are distributed and wound around each teeth of the second system stator 13B so that the amplitudes of those induced AC voltages are mutually different 90 degrees in the electrical angle. The second system excitation winding 10B is distributed and wound around each teeth of the second system stator 13B. The teeth number of the first system stator 13A and the teeth number of the second system stator 13B may be the same numbers, or may be the different numbers.

Even using the configuration of this kind resolver 1, by performing the similar processing as the controller 50 of Embodiment 1 or 2, even if the magnetic interference between systems occurs, the first angle θ1, the second angle θ2, the DC values of first system two output signals V1A_DC, V2A_DC, and the DC values of second system two output signals V1B_DC, V2B_DC are detected with good accuracy.

4. Other Embodiments

Lastly, other embodiments of the present disclosure will be explained. Each of the configurations of embodiments to be explained below is not limited to be separately utilized but can be utilized in combination with the configurations of other embodiments as long as no discrepancy occurs.

(1) The first system and the second system may be replaced. That is to say, the first system of each of above embodiments may be set to the second system; and the second system of each of above embodiments may be set to the first system.

(2) In each of the above-mentioned embodiments, there was explained the case where the first system reduction processing unit 53A performs the addition processing of this time detection value and the detection value before the first system reduction processing interval ΔT1, as the second period component reduction processing which reduces the component of the second period included in the detection values of output signals of first system two output windings; and the second system reduction processing unit 53B performs the subtraction processing or the addition processing of this time detection value and the detection value before the second system reduction processing interval ΔT2, as the first period component reduction processing which reduces the component of the first period included in the detection values of output signals of second system two output windings. However, embodiments of the present disclosure are not limited to the foregoing case. That is to say, the first system reduction processing unit 53A may perform a band reduction filter processing such as a high pass filter processing or a band stop filter processing which reduces the component of the second period, as the second period component reduction processing. The second system reduction processing unit 53B may perform a band reduction filter processing such as a low pass filter processing or a band stop filter processing which reduces the component of the first period, as the first period component reduction processing.

(3) In each of the above-mentioned Embodiments, there been explained the case where the one controller 50 is provided with the processing units 51A to 56A of the first system, and the processing units 51B to 56B of the second system. However, embodiments of the present disclosure are not limited to the foregoing case. That is to say, a controller of the first system may be provided with the processing units 51A to 56A of the first system, and a controller of the second system may be provided with the processing units 51B to 56B of the second system, or a plurality of controllers may be distributedly provided with each processing units 51A to 56B of the first system and the second system.

(4) In each of the above-mentioned embodiments, there was explained the case where the first system output signal detection unit 52A detects the output signals of first system two output windings V1A, V2A at every the first period TA when the excitation AC voltage VRA becomes the maximum value. However, embodiments of the present disclosure are not limited to the foregoing case. That is to say, the first system output signal detection unit 52A may detect the output signals of first system two output windings V1A, V2A at every the first period TA when the excitation AC voltage VRA becomes the minimum value, or may detect at every the first period TA when the excitation AC voltage VRA becomes other than the maximum value and the minimum value as mentioned above. Alternatively, the first system output signal detection unit 52A may detect at every the half period TA/2 of the first period when the excitation AC voltage VRA becomes the maximum value or the minimum value. Alternatively, the first system output signal detection unit 52A may the detect output signals of first system two output windings V1A, V2A at every period (for example, a period obtained by dividing the first system reduction processing interval ΔT1 by an integer greater than or equal to one) which is different from the first period TA and the half period TA/2 of the first period. Also in these cases, the first delay device 53A1 and the second delay device 53A2 of the first system reduction processing unit 53A delays the input signal by the first system reduction processing interval ΔT1 and outputs.

(5) In above-mentioned Embodiment 1, there was explained the case where the second system output signal detection unit 52B detects the output signals of second system two output windings V1B, V2B at every the half period TB/2 of the second period when the excitation AC voltage VRB becomes the maximum value or the minimum value. However, embodiments of the present disclosure are not limited to the foregoing case. That is to say, as mentioned above, the second system output signal detection unit 52B may detect at every half period TB/2 of the second period when the excitation AC voltage VRB becomes other than the maximum value and the minimum value. Alternatively, the second system output signal detection unit 52B may the detect output signals of second system two output windings V1B, V2B at every period (for example, a period obtained by dividing the second system reduction processing interval ΔT2 by an integer greater than or equal to one) which is different from the half period TB/2 of the second period. Also in these cases, the first delay device 53B1 and the second delay device 53B2 of the second system reduction processing unit 53B delays the input signal by the second system reduction processing interval ΔT2 and outputs.

(6) In above-mentioned Embodiment 2, there was explained the case where the second system output signal detection unit 52B detects the output signals V1B, V2B of the second system two output windings at every ¼ period TB/4 of the second period; and each detection timing is set so as to become before-and-after symmetrical with respect to the reference timing TM0 when the AC voltage VRB of the second period TB becomes the maximum value or the minimum value. However, embodiments of the present disclosure are not limited to the foregoing case. That is to say, the second system output signal detection unit 52B may detect periodically the output signals V1B, V2B of the second system two output windings at two timings which become before-and-after symmetrical with respect to a reference timing TM0 when the excitation AC voltage VRB becomes the maximum value. Alternatively, the second system output signal detection unit 52B may detect periodically the output signals V1B, V2B of the second system two output windings at two timings which become before-and-after symmetrical with respect to a reference timing TM0 when the excitation AC voltage VRB becomes the minimum value. As long as the interval between two timings which become before-and-after symmetry is set to the second system reduction processing interval ΔT2, it may be set to an interval other than ¼ period TB/4 of the second period. Also in these cases, the first delay device 53B1 and the second delay device 53B2 of the second system reduction processing unit 53B may delay the input signal by the second system reduction processing interval ΔT2 and output; and the second system reduction processing unit 53B may perform the addition processing at the later timing TM2 with respect to the reference timing TM0 and calculate the detection values of output signals of second system two output windings V1B_F, V2B_F after addition.

(7) As the angle detection apparatus for a motor which is provided with two sets of three-phase windings and inverters, the angle detection apparatus according to the present disclosure may be used. This kind of dual system motor is provided in an electric power steering apparatus, for example. The configuration of the first system of the angle detection apparatus of the present disclosure is assigned to the control system of the first set of three-phase winding and inverter, and the first angle θ1 is used for it. The configuration of the second system of the angle detection apparatus of the present disclosure is assigned to the control system of the second set of three-phase winding and inverter, and the second angle θ2 is used for it. Then, when the abnormality of first system of the angle detection apparatus is detected, control of the first set of three-phase winding and inverter is stopped. When the abnormality of second system of the angle detection apparatus is detected, control of the second set of three-phase winding and inverter is stopped. Since it is not necessary to synchronize the first system and the second system in the angle detection apparatus of the present disclosure, it may be configure that the first set of three-phase winding and inverter, and the first system of angle detection apparatus are controlled by a first controller (CPU), and the second set of three-phase winding and inverter, and the second system of angle detection apparatus are controlled by a second controller (CPU). Accordingly, system including the angle detection apparatus can be made redundant, and reliability can be improved.

Although the present disclosure is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead can be applied, alone or in various combinations to one or more of the embodiments. It is therefore understood that numerous modifications which have not been exemplified can be devised without departing from the scope of the present disclosure. For example, at least one of the constituent components may be modified, added, or eliminated. At least one of the constituent components mentioned in at least one of the preferred embodiments may be selected and combined with the constituent components mentioned in another preferred embodiment.

REFERENCE SIGNS LIST

-   -   1 Resolver, 10A First system excitation winding, 10B Second         system excitation winding, 111A, 112A First system two output         windings, 111B, 112B Second system two output windings, 51A         First system excitation unit, 52A First system output signal         detection unit, 53A First system reduction processing unit, 54A         First system angle calculation unit, 55A First system DC         extraction processing unit, 56A First system abnormality         detection unit, 51B Second system excitation unit, 52B Second         system output signal detection unit, 53B Second system reduction         processing unit, 54B Second system angle calculation unit, 55B         Second system DC extraction processing unit, 56B Second system         abnormality detection unit, TA First period, TB Second period,         ΔT1 First system reduction processing interval, ΔT2 Second         system reduction processing interval, V1A_S, V2A_S Detection         values of the first system two output signals, V1A_F, V2A_F         Detection values of the first system two output signals after         the second period component reduction processing, V1A_DC, V2A_DC         DC values of first system two output signals, V1A_TA, V2A_TA         Components of the first period included in the output signals of         first system two output windings, V1A_TB, V2A_TB Components of         the second period included in the output signals of first system         two output windings, V1B_S, V2B_S Detection values of the second         system two output signals, V1B_F, V2B_F Detection values of the         second system two output signals after the first period         component reduction processing, V1B_DC, V2B_DC DC values of         second system two output signals, V1B_TA, V2B_TA Components of         the first period included in the output signals of second system         two output windings, V1B_TB, V2B_TB Components of the second         period included in the output signals of second system two         output windings 

1. An abnormality detection apparatus for resolver comprising: a resolver that is provided with a first system excitation winding, first system two output windings, a second system excitation winding, and second system two output windings, in which magnetic interference occurs between a first system and a second system; a first system exciter that applies AC voltage of a first period to the first system excitation winding; a second system exciter that applies AC voltage of a second period different from the first period, to the second system excitation winding; a first system output signal detector that detects output signals of the first system two output windings at a period less than or equal to half of the first period; a first system reduction processor that performs a second period component reduction processing which reduces component of the second period, to detection values of the output signals of the first system two output windings; a first system DC extraction processor that calculates DC values of the first system two output signals, by performing a DC extraction processing which reduces component of the first period, to the detection values of output signals of first system two output windings after the second period component reduction processing; and a first system abnormality detector that determines abnormality of first system, based on whether or not the DC values of first system two output signals are within a preliminarily set normal range of first system.
 2. The abnormality detection apparatus for resolver according to claim 1, wherein, when a case where the DC values of first system two output signals are not within the normal range of first system occurs continuously a preliminarily set abnormality determination frequency or more, the first system abnormality detector determines that abnormality occurs in the first system.
 3. The abnormality detection apparatus for resolver according to claim 1, wherein the first system DC extraction processor calculates the DC values of first system two output signals, by performing a moving average processing during a period of a natural number times of the first period, to the detection values of output signals of first system two output windings after the second period component reduction processing.
 4. The abnormality detection apparatus for resolver according to claim 1, wherein the first system output signal detector detects the output signals of first system two output windings at a detection timing of every half period of the first period when the AC voltage of the first period applied to the first system excitation winding becomes the maximum value or the minimum value, and wherein the first system DC extraction processor calculates, as the DC values of first system two output signals, average values of the detection values of output signals of first system two output windings after the second period component reduction processing calculated at this time detection timing, and the detection values of output signals of first system two output windings after the second period component reduction processing calculated at the last time detection timing.
 5. The abnormality detection apparatus for resolver according to claim 1, wherein the second period is set longer than the first period, wherein the first system reduction processor, as the second period component reduction processing, adds the detection values of output signals of first system two output windings detected at this time detection timing, and the detection values of output signals of first system two output windings detected at a detection timing earlier by a first system reduction processing interval than this time detection timing, and wherein when setting the second period to TB, the first system reduction processing interval is set to TB/2+TB×M (M is an integer greater than or equal to 0).
 6. The abnormality detection apparatus for resolver according to claim 5, wherein when setting the first period to TA, the second period is set to TA×2×N (N is greater than or equal to 1).
 7. The abnormality detection apparatus for resolver according to claim 1, further comprising: a second system output signal detector that detects output signals of the second system two output windings at a period less than or equal to half of the second period; a second system reduction processor that performs a first period component reduction processing which reduces component of the first period, to detection values of the output signals of second system two output windings; a second system DC extraction processor that calculates DC values of second system two output signals, by performing a DC extraction processing which reduces component of the second period, to the detection values of output signals of second system two output windings after the first period component reduction processing; and a second system abnormality detector that determines abnormality of second system, based on whether or not the DC values of second system two output signals are within a preliminarily set normal range of second system.
 8. The abnormality detection apparatus for resolver according to claim 7, wherein, when a case where the DC values of second system two output signals are not within the normal range of second system occurs continuously a preliminarily set abnormality determination frequency or more.
 9. The abnormality detection apparatus for resolver according to claim 7, wherein the second system DC extraction processor calculates the DC values of second system two output signals, by performing a moving average processing during a period of a natural number times of the second period, to the detection values of output signals of second system two output windings after the first period component reduction processing.
 10. The abnormality detection apparatus for resolver according to claim 7, wherein the second system output signal detector detects the output signals of second system two output windings at a detection timing of every half period of the second period when the AC voltage of the second period applied to the second system excitation winding becomes the maximum value or the minimum value, and wherein the second system DC extraction processor calculates, as the DC values of second system two output signals, average values of the detection values of output signals of second system two output windings after the first period component reduction processing calculated at this time detection timing, and the detection values of output signals of second system two output windings after the first period component reduction processing calculated at the last time detection timing.
 11. The abnormality detection apparatus for resolver according to claim 7, wherein the second system reduction processor performs, as the first period component reduction processing, a subtraction processing which calculates differences between the detection values of output signals of second system two output windings detected at this time detection timing and the detection values of output signals of second system two output windings detected at a detection timing earlier by a second system reduction processing interval than this time detection timing, and wherein when setting the first period to TA, the second system reduction processing interval is set to TA×P (P is an integer greater than or equal to 1).
 12. The abnormality detection apparatus for resolver according to claim 11, wherein when setting the first period to TA, the second period is set to TA×2×N (N is greater than or equal to 1); and wherein when setting the second period to TB, the second system reduction processing interval is set to TB/2+TB×L (L is an integer greater than or equal to 0).
 13. The abnormality detection apparatus for resolver according to claim 7, wherein the second system reduction processor, as the first period component reduction processing, adds the detection values of output signals of second system two output windings detected at this time detection timing, and the detection values of output signals of second system two output windings detected at a detection timing earlier by a second system reduction processing interval than this time detection timing, and wherein when setting the first period to TA, the second system reduction processing interval is set to TA/2+TA×X (X is an integer greater than or equal to 0).
 14. The abnormality detection apparatus for resolver according to claim 13, wherein the second system output signal detector detects periodically the output signals of second system two output windings at two timings which become before-and-after symmetrical with respect to a reference timing when the AC voltage of the second period applied to the second system excitation winding becomes the maximum value or the minimum value, wherein an interval of the two timings is set to the second system reduction processing interval, and wherein the second system reduction processor adds the detection values of output signals of second system two output windings detected at the two timings with each other, at later timing of the two timings.
 15. The abnormality detection apparatus for resolver according to claim 14, wherein the second system output signal detector detects the output signals of second system two output windings at a detection timing of every ¼ period of the second period, and wherein the second system DC extraction processor calculates, as the DC values of second system two output signals, average values of the detection values of output signals of second system two output windings after the first period component reduction processing calculated at the later timing of this time two timings, and the detection values of output signals of second system two output windings after the first period component reduction processing calculated at the later timing of last time two timings.
 16. The abnormality detection apparatus for resolver according to claim 1, wherein the first system excitation winding, the first system two output windings, the second system excitation winding, and the second system two output windings are wound around the same one stator.
 17. The abnormality detection apparatus for resolver according to claim 1, wherein the first system excitation winding and the first system two output windings are wound around a first system stator; and the second system excitation winding and the second system two output windings are wound around a second system stator which adjoins the first system stator in an axial direction. 